1. Field of the Invention
The present invention relates to transition control of images displayed with an image display apparatus.
2. Description of the Related Art
Projectors for projecting and displaying images (projection-type display apparatuses) are widely used in various presentations. The projector causes a personal computer (hereinafter referred to as ‘PC’) to execute software for supporting presentation (hereinafter referred to as the ‘presentation tool’), and reproduces and displays an image expressed by video data in data prepared in advance for presentation (hereinafter referred to as the ‘presentation data’). One typical example of the presentation tool is PowerPoint (registered trademark) by Microsoft Inc.
Some recently developed projectors do not utilize the PC functioning as the image reproduction apparatus (player) but are self-contained to perform presentation. Such a projector is hereinafter referred to as the ‘projector with the player’. The projector with the player has an interface communicable with a memory card like a PC card and enables display of an image expressed by video data included in presentation data stored in the memory card.
The player mounted on the projector is not the PC executing the software program PowerPoint but only has the restricted function to reproduce an image expressed by video data included in the presentation data stored in the memory card. For example, the player displays the respective images expressed by the video data stored in the memory card on the basis of the JPEG or BMP format as individual slides.
The software program PowerPoint is capable of specifying diverse display effects (hereinafter may also be referred to as ‘image transition effects’) in the process of switching over the slides to draw attention in the presentation. The display effects depend upon how a resulting display image (image C) is generated in the course of changing the display from a current on-screen image (image A) to a next on-screen image (image B). More specifically, the display effects depend upon the selection for a pixel ‘c’ of the image C, that is, which of a pixel ‘a’ included in the image A, a pixel ‘b’ included in the image B, and an operation result of the pixels ‘a’ and ‘b’ is set to the pixel ‘c’ of the image C. Such display effects include animation effects like fade-in, fad-out, slide-in, wipe, and blind.
The projector with the player has a hardware configuration in the player for selecting the output video data with regard to each pixel, based on the mask data having the identical size with that of the output video data. This attains the similar display effects to those attained by the software program PowerPoint.
The prior art projector with the player uses the mask data having the same size as that of the video data and thus requires a large storage capacity for storing the mask data. Multiple mask data are generally required to attain one display effect, and this causes further expansion of the required storage capacity. The expansion of the required storage capacity undesirably increases the frequency of access to the memory for rewriting the mask data. This results in heavy load applied to a CPU that gains access to the memory and interferes with the high-speed processing. This problem is common to any image display apparatuses exerting similar display effects.